Method of making a humidifier evaporating element



Aug. 25, 1970 R. W. ABBOTT METHOD OF MAKING A HUMIDIFIER EVAPORATING ELEMENT Filed April 9. 1968 FIG. 4

INVENTOR.

ROY W. ABBQTT arm ms ATTORNEY United States Patent US. Cl. 29-157 3 Claims ABSTRACT OF THE DISCLOSURE An evaporating element for a humidifier where the element has a metallic pad that is made by slitting the edges of a narrow strip of thin sheet metal to provide a plurality of slender, spine fin members each connected with a center strip or spinal column extending longitudinally of the strip. The plane of the strip is corrugated at an acute angle with respect to the longitudinal axis of the strip, then the strip is pleated and pressed into layers to form a pad that is about as high as it is wide. Finally, a reinforcing frame encompasses the periphery of the pad, and there is a water trough formed in the top of the frame from which water is allowed to drain slowly onto the entire pad.

CROSS-REFERENCE TO RELATED APPLICATION The present invention of an evaporating element for a humidifier is adapted for use with a humidifier design such as is disclosed in the copending patent application a humidifier is adapted for use with a humidifier design Ser. No. 667,831 entitled Dual-Mount Furnace Humidifier of the present applicant and Donald M. Mullings, which was filed in the Patent Office on Sept. 14, 1967, and which is now Pat. No. 3,437,318.

BACKGROUND OF THE INVENTION There are many annoying effects resulting from heating rooms with forced warm air that has not been humidified. For example, dry heated air recirculating through the furnace system absorbs moisture from the human body causing the body to feel cool and chilly even though the temperature is relatively high. Since dry air requires higher temperatures for comfort than does humidified air, there is also a substantial increase in expenditures for fuel required to heat comfortably with non-humidified air. Moreover, dry room climate may result in discomfort in the nose and throat areas of the occupants as well as restricted breathing passages and chronic coughing conditions.

These deleterious effects are substantially avoided by installing a humidifier in the furnace plenum or warm air distribution duct of the heating system. The humidifier must be located on the supply or warm air side of the furnace and it must be furnished with a power cable, water supply line and a water drain line. The main elements of a furnace humidifier are an evaporating element and a motor driven fan and means for wetting the element so that the warm air is caused to pass through the element and pick up a percentage of the moisture from the element before the warm air proceeds through the distribution duct. The fan motor is customarily wired from a source of electrical power in a manner to operate 3,525,138 Patented Aug. 25, 1970 ice only when the furnace blower is operating. In addition, a humidistat is furnished with the humidifier and it controls a solenoid water valve that governs the amount of water furnished to the evaporating element. The humidistat would be connected in series with the fan motor and solenoid valve. Hence, if the humidity is high in the cool air return duct of the furnace system, the humidistat will open the circuit to the solenoid valve and fan motor even though the furnace blower may be running. A slight amount of excess water is allowed to drain from the evaporating element and accumulate in a sump in the bottom of the humidifier housing, and this overflow is removed through a drain connection leading from the sump.

The evaporating element of the present invention has a metallic pad that is made of metal strip having high surface area and a high rate of evaporation without having the undesirable features of promoting bacterial growth, fungus, creating a fire hazard or an odor problem. It also has a low resistance to air fiow when wet or dry. In an evaporating element of the class described it is necessary to provide a large amount of wetted surface area. Hydrophilic materials have been used successfully in the past when constructed in such a manner as to provide sufiicient surface area because water was drawn over the entire surface. However, materials of this sort, such as flocked foam or wood excelsior, are generally considered undesirable because they support bacterial growth, fungus and are considered as possible fire hazards. Metals and other non-organic materials are desirable since they eliminate the above undesirable features, but they are hydrophobic by nature, which means they are difficult to wet.

One of the most difficult problems in automatic humidifiers, especially those combined with a residential heating system, arises from the buildup of mineral residue. The tap water available contains various quantities of minerals depending upon its source. During the continual evaporation of the water these minerals remain in the evaporating element in the form of lime or sodium crust which eventually must either be removed or they will cause the system to clog and possible flooding of the ducts of the furnace system.

The principal object of the present invention is to provide an evaporating element for a humidifier with a wettable pad formed of metal strip with spine fin members for holding the water by capillary action.

A further object of the present invention is to provide an evaporating element of the class described with a wettable pad of layers of metal strips having a selfspacing feature to provide a low resistance to air flow through the pad.

A still further object of the present invention is to provide an evaporating element of the class described with a wettable pad of metal strips which can be made at a nominal cost such that the element may be considered as being readily disposable when its efficiency has been substantially reduced by the accumulation of mineral deposits.

SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof, relates to the art of furnace humidifiers and in particular to an evaporating element having a metallic pad that is adapted to be water soaked. The pad is made by a method comprising the steps of slitting the edges of a narrow strip of thin sheet metal stock, while retaining a central spinal column extending longitudinally of the strip. Next the strip is corrugated at an acute angle with respect to the longitudinal axis of the strip. Then the strip is arranged in a plurality of alternating layers on top of each other to form a wettable pad of high surface area where the corrugations serve a selfspacing function. Then the pad is installed in a supporting frame.

BRIEF DESCRIPTION OF THE DRAWING My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIG. 1 is a schematic perspective view showing slitting rolls for slitting the edges of a strip of sheet metal stock while retaining a longitudinal center strip, and then helical gears for corrugating the plane of the strips at an acute angle with respect to the longitudinal axis of the strip, and finally folding the corrugated strip back on itself in a pleating operation.

FIG. 2 is a fragmentary side view on an enlarged scale of the slitting rolls, illustrating the side edge slitting operation as the thin sheet metal strip is drawn between the rolls.

FIG. 3 is a fragmentary perspective view of a short 7 length of the sheet metal strip on an enlarged scale showing the slits that are formed in the side edges of the strip as well as the central longitudinally extending spinal column which supports a plurality of spine fin members.

FIG. 4 is a fragmentary elevational view of the upper left hand corner of a disposable evaporating element for a humidifier which utilizes the reversed layers of narrow sheet metal strip having spine fins of the present invention for retaining the water by a capillary action.

FIG. 5 is a fragmentary, cross-sectional, elevational view at the top edge of the evaporating element of FIG. 4 to show the perforated water trough and felt pad underlying the same for wetting the metallic evaporating pad.

FIG. 6 is a fragmentary, plan view of the narrow strip of thin sheet metal similar to that of FIG. 3, but after the plane of the strip is corrugated at an acute angle with respect to the longitudinal axis of the strip.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to a consideration of the drawings and in particular to FIG. 1, there is shown schematically the first step of the method of preparing a narrow strip 10 of thin sheet metal such as aluminum so that it has spine fins on the side edges. The plain strip of material 10 is a narrow strip of about one inch width having a thickness of about .007 inch. The strip is drawn through a pair of slitting rolls 12 and 14 which are each provided with sharp cutting teeth 15, as is best seen in FIG. 2, so as to slit or lance the side edges of the strip to form slender spine fins 11. It would not do to slit the strip from one side to the other because this would sever the strip. The slit is marked 16. What is done is each slit 16, as seen in the enlarged view of FIG. 3, stops short of the longitudinal center line of the strip so as to form a central spinal column 17 that extends longitudinally of the strip 10 for the entire length thereof. The slitting rolls 12 and 14 are both drive rollers and they cause the strip 10 to be pulled therethrough from a source of the strip material; for instance, a large coil that is several feet in diameter, which is the usual form it is received from the metal supplier.

After the slitting operation is performed the slit tape, which may be designated 18, is pulled through a second set of drive rollers or helical gears 22 and 24 that are 4 provided with large teeth 26 such that the slit tape 18 is provided with a uniform series of corrugations 28 that extend from one side to the other of the strip at an acute angle with respect to the longitudinal axis of the strip. It should be understood that the act of corrugating the strip labeled 30 tends to frazzle the tips 31 of the spine fins 11. Unfortunately, this is difficult to illustrate in a patent drawing of this type, as it is much easier to draw symmetrical or uniform surfaces than it is frazzled or haphazard edges. Hence, it requires some imagination of the reader to visualize the actual appearance of the finished slit, corrugated metal strip 30 of the present invention. A better showing than FIG. 1 is made in FIG. 6.

The next step is to fold the slit, corrugated strip 30, as along the fold line 32, so that the strip is folded back on itself and this action is repeated at substantially equal lengths along the strip, but in opposite directions, so that in elfect the strip is alternately folded or pleated to build up layers of the slit corrugated strip 30. Hence the crisscross corrugations 28 serve a self-spacing function. These layers are best seen in FIG. 4, and they are of such an extent as to have a height that is substantially equal to the width of the folded or pleated strips to form an evaporating pad 35. Of course, this height-to-width ratio is not a critical limitation, but merely an example of the preferred embodiment of the present invention. Also as seen in FIG. 4, the evaporating pad 35 is reinforced by a supporting frame 37 of light sheet metal stock, such as aluminum, of generally channel-shape, transverse crosssection which is folded around the periphery of the evapcrating pad 35, especially along the two sides and the bottom edge thereof. The top edge 39 is different from the other three sides in that it is shaped in the form of a V-shaped trough 40 as is seen in FIG. 5 for receiving and holding a supply of water. The trough 40 is provided with a series of spaced holes 41 along the extent thereof. Disposed beneath the apex of the V-trough 40 is an elongated felt pad 43 which is adapted to underlie at least the lower portion of the holes 41 so as to become soaked by the water and drain in a slow uniform fashion onto the top layer of the evaporating pad 35. Of course, one of the main purposes of the felt pad is to serve as a stopper to prevent the trough from emptying suddenly as it is being filled, and also to slow down the drainage of the water onto the evaporating pad 35. In other words, the trough is not a bottomless container. In operation, water is accumulated on the central spinal column 17 of the slit, corrugated strip 30 and drawn out over the slits 16 between the spine fins 11 by capillary action and made to wet the entire spine fin. If the spine fins are made too wide, the slit between them will be too wide for the water to bridge due to its surface tension. A preferred width of a spine fin is about .030 inch.

Modifications of this invention will occur to those skilled in this art. Therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of making an evaporating element for a humidifier, said method comprising the steps of providing a narrow strip of thin sheet metal stock, slitting said strip of sheet stock inwardly from its opposite edges toward the center thereof at closely spaced intervals to provide a plurality of slender spine fin members each connected with a center spinal column extending longitudinally of the strip, then corrugating the plane of the slit strip at an acute angle with respect to the longitudinal axis of the strip, and alternately folding the strip at generally equally spaced lengths of the strip to build up a plurality of layers of the strip material, and installing a supporting frame around the folded layers of the strip material to create a self-supporting evaporating element.

2. The method of making an evaporating element for a humidifier, said method comprising the steps of providing a narrow strip of thin sheet metal stock, lancing the side edges of the strip to create a plurality of slender spine fin member which are supported from a central spinal column extending longitudinally of the strip, corrugating the plane of the lanced strip Where the corrugations extend at an acute angle to the longitudinal axis of the strip, alternately folding the corrugated strip over on itself at generally equally spaced lengths of the strip to build up a pad that is generally as high as it is wide, and installing a frame around the periphery of the pad to hold the layer together, and providing the top run of the frame with a perforated trough whereby water may be supplied to the trough and will drain slowly onto the evaporating pad and flows onto the center spine of the strip and is drawn out onto the spine fin members by capillary action.

3. The method of making a disposable evaporating pad for a humidifier, said method comprising steps of providing a narrow strip of thin sheet metal, slitting the opposite edges of the strip to form a plurality of slender, spine fin members while retaining a central spinal column extending longitudinally of the strip, corrugating the plane of the lanced strip where the corrugations extend at an acute angle with respect to the longitudinal axis of the strip, alternately laying portions of the corrugated strip on top of each other to form a wettable pad of high surface area, where the corrugations serve a self-spacing function, and providing a supporting frame around the pad to hold the corrugated layers together.

References Cited UNITED STATES PATENTS JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner US. Cl. X.R. 113l16;72326 

